KR960013127B1 - Polymer blends of polycarbonate and polyamide and process thereof - Google Patents

Abstract

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Description

Polymer blend of polycarbonate and polyamide and process for preparing same

The present invention relates generally to compatibilizers for polymer blends of polycarbonates and polyamides, characterized in that melt blended blends have improved physical and chemical properties, and to methods of making such blends.

Polymeric resins have long been known for their chemical and physical properties. Molded or extruded resins have been found in many agglomerated products such as electrical appliances, consumer products, electronics, mechanical components, automotive parts and the like. However, the physical and chemical properties of the polymer resins and the components or articles made therefrom vary widely, depending on the structure of the polymer resin backbone as well as the molecular weight of these polymer resins.

For example, polycarbonate resins are known to have thermal distortion temperatures, but these polymer resins and articles molded or extruded from them generally have low chemical resistance to solvents, low crack resistance to stress, and thick polymer parts. Has low impact strength when needed or used.

Polymeric resins, such as polyamides (such as nylon), on the other hand, are known to be chemically resistant to many solvents and to the required degree of toughness and wear resistance. However, polyamides also have inherent drawbacks, such as low impact strength, low heat distortion temperature, and water absorption, unless modified.

Mixtures of selected polymeric resins were used in the blend formation to modify the properties of the polymeric resin. In many cases, however, polycarbonate and polyamide resins and such resins are incompatible. Attempts to impart compatibility to such resin materials generally involve expensive compounds or process conditions, and even the resin blends obtained often do not possess the necessary properties. Therefore, if an effective and economical method or compatibilizer can be found that can make polycarbonate resin compatible with polyamide or nylon resin without sacrificing the properties required for each resin material forming the blend, It would be an extremely desirable and important step forward.

It is an object of the present invention to provide a compatibilizer for polycarbonates and polyamide resins which makes it possible to obtain polymer blends from these materials without sacrificing the properties required for each resin to be used in the blend.

Yet another object of the present invention is to provide an economical process for producing blends of polycarbonates and polyamides using conventional mixing devices while achieving the objects discussed above.

Other objects, advantages and features of the invention will become apparent from the following detailed description when read in conjunction with the appended claims.

The present invention therefore relates to compatibilizers for polycarbonate and polyamide polymer blends that allow improved physical and chemical resistance to the blend without substantially sacrificing the properties required for the polycarbonate or polyamide. These polymer blends have the properties required for each component forming the blend, namely improved resistance to solvents and stress crackers, fairly high impact strength and thermal distortion temperatures and the polymer blends have no affinity for water absorption. .

Polymer blends of polyamides such as nylon having the above-mentioned properties and polycarbonates generally have a molecular weight of about 20 to about 90% by weight of polycarbonate having a molecular weight of about 20,000 to about 40,000, and a molecular weight of at least about 2,000. From about 75 to about 5 weight percent polyamide and from about 20 to about 2 weight percent polymeric compatibilizer having at least one functional group soluble in polycarbonate and at least one functional group soluble in polyamide.

Polymeric compatibilizers for polycarbonate and polyamide blends are linear segmented thermoplastics with semi-crystalline solid segments and ester segments, which are generally partially aromatic polyamides based on polyetherimide, polyurethane and diphenylmethane diisocyanate. About 10 to 90 weight percent of the compound selected from the elastomer; From about 90 to about 10 weight percent of the blend of polymer grafted with maleic anhydride; And from about 0 to about 80 weight percent of the alloying agent. Preferably the melting point or softening point of this compatibilizer is no greater than the melting or softening point of the polycarbonate and polyamide resins that are constituents of this blend.

The present invention provides a process for the preparation of a polymer blend of polycarbonate and polyamide comprising:

(a) from about 20 to about 90 weight percent of a polycarbonate having a molecular weight of about 20,000 to about 40,000 and from about 70 to about 5 weight percent of a linear polyamide having a molecular weight of at least 2,000, and to the polycarbonate From about 20% to about 2% by weight of a polymeric emollient having at least one functional group and at least one functional group soluble in the polyamide for an effective time to form a substantially homogeneous mixture; And

(b) Injecting the homogeneous mixture into the compounding extruder to form a blend to produce a polycarbonate-polyamide melt blended blend having the properties required for each of the components. The compounding extruder is operated with improved mixing of the blend components and the components at temperatures above the melting point and with a wide range of shear forces.

The term blend, as used herein, refers to a substantially uniform mass of material and is obtained by pellet extrudates heating these materials to melting or softening points under high shear conditions in an extruder. Unexpectedly the chemical and physical properties required for each constituent are blends of the present invention that are generally present in about 20 to about 90 weight percent polycarbonate, about 70 to about 5 weight percent linear polyamide, and polycarbonate And from about 20 to about 2 weight percent of a polymeric compatibilizer having at least one soluble functional group and at least one functional group soluble in the polyamide. Such compatibilizers are generally convex copolymers and blends containing such convex copolymers and the convex copolymer serves as an interfacial component between the two incompatible components.

The polycarbonates that may be used in the blend formulations of the present invention may be any suitable polycarbonate that is well known in the art and has a molecular weight of about 20,000 to about 40,000. Similarly, linear polyamides that can be used in the blend formulations of the present invention include those semi-crystalline and amorphous resins well known in the art that have a molecular weight of at least 2,000 and are commonly called nylon. Preferably, the polyamide resin has a molecular weight of at least about 5,000 and includes polyamides such as polycaprolactam (6 nylon), polyhexamethylene adipamide (66 nylon), polyhexamethylene azelamide (69 nylon) and the like Include.

In order for the polycarbonate component to be compatible with the polyamide component of the blend, the polymeric compatibilizer must have at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide. The amount of polymeric compatibilizer included in this blend can vary widely but is generally in an amount of about 2 to about 20% by weight of the blend. Furthermore, it is important that the blend is melt blended, so that the melting point or softening point of the polymer compatibilizer is not higher than the melting point or softening point of the polycarbonate and polyamide constituting the blend. Suitable compounds that meet the criteria described above can be used as polymer compatibilizers in the formulation of the polycarbonate-polyamide blends of the present invention. However, preferred results are obtained when the polymer compatibilizer comprises:

(a) a linear segmented thermoplastic elastomer, polyurethane having a semicrystalline hard segment and ester segment, which is a diphenylmethane diisocyanate based and partially aromatic polyamide, such as the elastomer marketed by Dow Chemical Company under the trademark Estamide 90A; 10-90 weight percent of polyether imide, preferably 15-75 weight percent, more preferably 20-55 weight percent;

(b) a polymer blend grafted with about 90 to 10, preferably 75 to 20, and more preferably 60 to 40 weight percent maleic anhydride; And

(c) 0 to about 80, preferably 25 to 75, and more preferably 30 to 50% by weight of alloying agent, using polyetherimide, polyurethane or linearly segmented thermoplastic elastomer as the only compatibilizer It is also possible (eg in amounts up to 100%). According to another embodiment of the invention, the polymeric compatibilizer comprises about 25 to about 50 weight percent of a linear segmented thermoplastic elastomer having a semicrystalline hard segment and an ester segment which are polyetherimide, polyurethane or partially aromatic polyamide. %, About 25 to about 50 weight percent of a polymeric blend grafted with maleic anhydride and a mixture of 0 to about 50 weight percent of an alloying agent.

Blends of the invention comprise polyetherimides of the general formula:

In this formula a represents one or more numbers, for example 10 to 10,000 or more, and the group is selected from:

R 'is hydrogen, lower alkyl or lower alkoxy and preferably the polyetherimide comprises -O-A wherein R' is hydrogen so that the polyetherimide is

And the divalent bond of the -O-Z-O radical is 3,3 '; 3,4 '; In position 4,3 'or 4,4'; Z is one of the following classes:

It is part of a class consisting of two organic radicals of the general formula:

In this formula, X is the part selected from the class consisting of divalent radicals of the formula:

Q is 0 or 1 and Y is 1-5; R is (1) aromatic hydrocarbon radicals having 6-20 carbon atoms and halogenated derivatives thereof, (2) alkylene radicals and cycloalkylene radicals having 2-20 carbon atoms, C _(2-8) alkylene And divalent organic radicals selected from the group consisting of terminal polydiorganosiloxanes, and (3) divalent radicals comprised of:

In this equation, Q is the selected part of the class consisting of

And x is 1-5. Particularly preferred polyetherimides for the purposes of the present invention include those wherein Z and Z are each of the formula:

And R is selected from:

Most preferred are polyetherimides in which R is metaphenylene.

Polyurethanes that can be used as polymer compatibilizers in the polycarbonate-polyamide blends of the present invention are diisocyanates and polyesters having a melting point lower than the process range used in the formulation of the compositions of the present invention, such as 480 ° F to 550 ° F. It is characterized by the reaction product of or polyester urethane elastomer. Examples of the polyurethane having the above characteristics and usable as a compatibilizer in the polymer blend of the present invention include PS 195-300, PN-03-100 and PS 440-100 manufactured by K.J. Quinn Company et al.

Polymer blends grafted with maleic anhydride that can be used as compatibilizers in the polycarbonate-polyamide blends of the present invention include blends of polypropylene grafted with maleic anhydride or ethylene propylene grafted with maleic anhydride; These may be prepared as any suitable grafting technique known in the art. Moreover, the amount of polypropylene grafted with maleic anhydride and maleic anhydride ethylene propylene in the grafted polymeric blend constituents of the polymeric compatibilizer varies widely. However, polypropylene rubbers grafted with maleic anhydride are generally in a weight ratio of about 0: 1 to about 5: 2 in the grafted polymer blend, and most preferably at about 1: 3 to 3: 1 by weight ratio. It exists in the weight ratio of 3: 2.

The alloying agent that may be used as one of the polymer compatibilizer components in the polycarbonate-polyamide blend may be any suitable alloying agent compatible with other components including polycarbonate, polyamide and the polymer compatibilizer. Generally, alloying agents that can be used as a component of a polymeric compatibilizer are thermoplastics that are compatible with polyamides or polycarbonates or both and improve the properties of the entire polymeric blend of the present invention such as cost, impact strength and processability. There is a characteristic as resin. Examples of thermoplastic resins that can be used as alloys include acrylonitrile-butadiene-styrene terpolymers, styrene-maleic anhydride copolymers, polyester elastomers, methacrylate-butadiene-styrene terpolymers, polymethacrylates, nitrile rubbers , Ionomers of polyethylene, polyether blockamides, polyphenylene oxide polymers and the like, as well as mixtures thereof.

The polyetheramides can be obtained by any method well known to those skilled in the art, including the reaction of any aromatic bis (mouse ether) of the formula:

In this formula, Z is defined above as the organic diamine of the following formula.

H ₂ NR-NH ₂

Where R is the same as defined above.

The aromatic bis (ether anhydride) of the above formula is, for example,

2,2- (bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride;

4,4'-bis (2,3-dicarboxyphenoxy) diphenyl ether dianhydride;

1,3-bis (2,3-dicarboxyphenoxy) benzene dianhydride;

4,4'-bis (2,3-dicarboxyphenoxy) diphenyl sulfide dianhydride;

1,4-bis (2,3-dicarboxyphenoxy) benzene dianhydride;

4,4'-bis (2,3-dicarboxyphenoxy) benzophenone dianhydride;

4,4'-bis (2,3-dicarboxyphenoxy) diphenylsulfone dianhydride;

2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride;

4,4'-bis (3,4-dicarboxyphenoxy) diphenyl ether dianhydride;

4,4'-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride;

1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride;

1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride;

4,4'-bis (3,4-dicarboxyphenoxy) benzophenone dianhydride;

4- (2,3-dicarboxyphenoxy) -4 '(3,4-dicarboxyphenoxy) diphenyl-2,2-propane dianhydride; And mixtures of these dianhydrides.

Also shown below are aromatic bis (anhydrous ether) containing the above formula; Koton, M.M. ; Florinski, F.S. ; Bessonov, M.I. ; Rudakov, A. P. (Institute of Heteroorganic Compounds, Academy of Sciences, U.S.S.R.), U.S.S.R. Patent No. 257,010, issued Nov. 11, 1969. 2 Anhydride M.M. Koton, F.S. Florinski, Zh Org, Khin, 4 (5), 774 (1968).

Examples of the organic diamines of the above-described type include m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl propane, 4,4'-diaminodiphenylmethane, benzidine, 4,4'- Diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethylbenzidine, 3,3'-dimeth Oxybenzidine, 2,4'-bis (beta-amino-t-butyl) toluene, bis (p-beta-amino-t-butylphenyl) ether, bis (p-beta-methyl-o-aminophenyl) benzene, 1,3-diamino-4-isopropylbenzene, 1,2-bis (3-aminopropoxy) ethane, m-xylenediamine, p-xylenediamine, 2,4-diaminotoluene, 2,6 -Diaminotoluene, bis (4-aminocyclohexyl) methane, 3-methylheptanmethylene-diamine, 4,4-dimethylheptamethylenediamine, 2,11-dodecanediamine, 2,2-dimethylpropylenediamine, octamethylene Diamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptane Tamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-cyclohexanediamine, 1,12-octadecane diamine, bis (3-aminopropyl) sulfide, N-methyl-bis (3 -Aminopropyl) amine, hexamethylenediamine, heptamethylenediamine, nonamethylenediamine, decamethylenediamine, bis (3-aminopropyl) tetramethyldisiloxane, bis (4-aminobutyl) tetramethyldisiloxane and the like and such Mixtures of diamines.

In general, the reaction can be advantageously carried out using well known solvents such as, for example, o-dichlorobenzene, m-cresol / toluene, etc., in which the interaction between the dianhydride and the diamine at a temperature of about 100 to 250 ° C. This happens. In addition, the polyetherimide can be prepared by mixing the dianhydride and the diamine compound at the same time and melt polymerization while heating the mixture of components at a high temperature. A polymerization terminator commonly used for melt polymerization may be added. The proportion of reaction conditions and components can vary widely depending on the required molecular weight, intrinsic viscosity and solvent resistance. Typically the same amount of diamines and dianhydrides are used for high molecular weight polyetherimides, but in some cases the molecules of the diamines are used in a slight excess (about 1 to 5 mole percent) to produce polyetherimides with amine groups at the ends. You can. Generally useful polyetherimides have an intrinsic viscosity of at least 0.2 dl, preferably 0.35 to 0.6 or 0.7 dl or more, as measured by m-cresol at 25 ° C.

Many methods of preparing polyetherimides include those disclosed in US Pat. Nos. 3,847,867, 3,847,869, 3,850,885, 3,852,242 and 3,855,178. This document is incorporated herein by reference in its entirety for the purpose of pointing to a general and specific method for preparing polyetherimides suitable for the blends of the present invention.

A convenient method for preparing a polymer blend of polycarbonate and polyamide of the present invention is substantially homogeneous by premixing the components (ie polycarbonate, polyamide and polymer compatibilizer) in suitable powder proportions and in fine powder form. A dry mixture is prepared and injected into a compounding extruder, heated to melt and extruded. Preferably the powdered or granular components are mixed in a low intensity mixer such as a ribbon mixer for an effective time until a substantially homogeneous or homogeneous mixture is obtained. While the time required to make a substantially homogeneous mixture varies very widely, the necessary results have been obtained when the mixing of the dry ingredients in the ribbon mixer is carried out for about 2 to about 5 minutes and more preferably about 2 to about 3 minutes.

This dry-mixed mixture is injected into a compounding extruder and heated to make the mixture substantially homogeneous plasticized material and extruded through the die head of the extruder to be stranded and then pelleted Cut into

Reciprocating mixers such as single screw or twin screw or Buss mixers can be used as the compounding extruder. However, twin screw extruders, such as Werner Pfleider WP ZSK 83 or Werner Pfleider ZSK 90 twin screw extruders, are preferred because twin screw extruders, such as extruders, are preferred because the molten material in these extruders achieves high shear forces. . In addition, high screw speeds, such as from about 100 to about 300 rpm, are required to allow the molten material to undergo high shear forces and to bring the components of the molten material into a substantially uniform mixture.

The compounding extruder is operated at a temperature and pressure sufficient to melt the components forming the blend to produce a molten material that can be extruded. Generally the compounding extruder is operated at a temperature of about 480 ° F. to about 550 ° F. and a pressure of about 500 psi to about 1500 psi and more preferably at a temperature of about 500 ° F. and a pressure of about 1000 psi.

The molten homogeneous material is sent through the compounding extruder where the plasticized homogeneous material passes through a number of holes in the diehead and is extruded into strands into the atmosphere. The die head of the compounding extruder is kept heated to a temperature of about 480 ° F. to about 550 ° F. in the compounding extruder of the molten material.

As discussed above, the extrudate contains a plurality of strands.

The strand is then cut into pellets. Pelletization of the extrudate is accomplished with a strand cutting pellet generator, such as a Cumberland pellet generator (cooled in a water bath prior to feeding the strands through the pellet generator), or with an underwater pellet generator, such as a Gala device (pellets are cut at the die face). You can. Pelletized polymer blends of polycarbonate and polyamide can then be used as raw materials to produce the necessary articles through molding or extrusion. Such molding and extrusion processes are known in the art.

Melt blended blends of polycarbonates, polyamides, and compatibilizers prepared according to the methods presented above have been found to have substantially eliminated the unnecessary properties of each component and have only the necessary properties of each component.

The following examples are set forth to more fully describe the invention. It should be understood, however, that this embodiment is for the purpose of description only and is not to be regarded as limiting the scope of the invention as defined in the appended claims.

A series of experiments were performed on articles molded from polymeric materials to determine the chemical and physical properties of these polymeric materials. The polymeric resin used to make the articles tested was a granular powder and dry mixed in a ribbon mixer for about 3 minutes to ensure that the components were thoroughly mixed to obtain a substantially uniform or homogeneous mixture.

This dry mixed mixture is then injected into a twin screw compounding extruder (eg Werner Pfleider WP ZSK 83 extruder), which is operated at approximately 1000 psi and has a yield of 200 lbs / hr. The screw speed, independently controlled for the extruder's production rate, was set at 150 RPM to ensure high shear forces on the molten polymer material in the extruder and to make the molten polymer material substantially homogeneous.

This molten polymer material or blend was extruded into strands through the die head of the compounding extruder. The strand was cooled through a water bath and then the strand was cut into pellets using a Cumberland pellet generator.

Typical temperature profiles for compounding extruders that gradually increase from the inlet to the diehead to form a substantially homogeneous blend to ensure proper melting and mixing of the polymeric components are:

The pellets obtained in each experiment were molded into articles to measure the chemical and physical properties of the polymeric materials and articles made therefrom. Table 1 shows each composition of the polymeric material; Table 2 is a compilation of test data relating to the physical properties of each of these polymer materials.

TABLE 1

* Linearly segmented thermoplastic elastomer, commercially available from Dow Chemical under the trademark Estamide 90A, based on diphenylmethane diisocyanate and having partially aromatic polyamide semi-crystalline hard and ester segments.

TABLE 2

Property data

* Physical properties could not be measured because the resin was incompatible.

A second series of tests were conducted to compare the physical and chemical properties of the polymer blends of polycarbonate polymers and polyamide polymers (nylon 6), including the compatibilizers formulated according to the present invention, and each component.

TABLE 3

* Linearly segmented thermoplastic elastomer, commercially available from Dow Chemical under the trademark Estamide 90A, based on diphenylmethane diisocyanate, partially aromatic polyamide, having semi-crystalline hard and ester segments.

TABLE 4

* Rapid Dri detergent manufactured by Sanolite Chemical

** WD-40 sold by WD-40

A third series of tests were performed to characterize the polymer blends of polycarbonate polymers, polyamide polymers, and compatibilizers made of ethylene-propylene rubber grafted with 33.3 wt% Estamid 90A and 66.7 wt% maleic anhydride. Was carried out. The proportions of these components are shown in Table 5 and the properties are shown in Table 6.

TABLE 5

The data clearly shows the improved physical and chemical properties imparted to the polymer blends of the present invention and articles made from such polymer blends. Moreover, the unique combination of polycarbonates, polyamides and compatibilizers in the formulation of the unique polymer blends of the present invention provides synergistic effects other than the chemical and physical properties of this polymer blend.

Finally, it is also possible to add other impact modifiers in the composition of the present invention together with or instead of the polymer grafted with maleic anhydride. Suitable impact modifiers include those disclosed in US Pat. No. 4,174,358, the contents of which are incorporated herein by reference.

Although it is obvious that the disclosed invention has been well calculated to meet the above-mentioned purposes, many embodiments and modifications are possible by one of ordinary skill in the art and the appended claims are directed to the present invention. It includes all such changes and embodiments that fall within the spirit and scope of this document.

Claims (10)

20 to 90% by weight of polycarbonate; 70 to 5 weight percent polyamide; And from 10 to 100% by weight of a compatibilizing compound of a hard segment of semi-crystalline aromatic polyamide based on polyurethane or diphenylmethane diisocyanate and a linear segmented thermoplastic elastomer having an ester segment, the compatibilizing compound being polycarbobo 20 to 2 weight percent polymer compatibilizer, having at least one functional group soluble in the nate and at least one functional group soluble in polyamide, consisting of 0 to 90 weight percent impact modifier, and 0 to 80 weight percent alloying agent, A polycarbonate and a poly, characterized in that the melting point or softening point of the polymer activator is not greater than the melting point or softening point of the polycarbonate and polyamide which are components of the blend to form a homogeneous blend of polycarbonate and polyamide. Blend compounded with an amide melt. 2. The compatibilizing agent according to claim 1, wherein the compatibilizer is a linear segmented thermoplastic elastomer having a hard segment and an ester segment of semicrystalline aromatic polyamide based on diphenylmethane diisocyanate, and a polypropylene and maleic anhydride grafted with maleic anhydride. A mixture of maleic anhydride grafted polymer blend of grafted ethylene-propylene rubber, so that the blend has a Gardner impact test value of at least 320, an Izod impact test value of at least 15 feet-lb, and a heat distortion temperature of at least 200 ° F. And blends characterized by excellent chemical resistance and crack resistance against stress. The polymer compatibilizer according to claim 1 or 2, wherein the polymer compatibilizer is 10 to 90% by weight of a linear segmented thermoplastic elastomer having a hard segment and an ester segment of a semicrystalline aromatic polyamide based on diphenylmethane diisocyanate, with maleic anhydride. A blend, characterized in that it comprises 90 to 10% by weight of an impact modifier of the grafted polymer blend. 4. The blend of claim 3 wherein the polymer blend graphed with maleic anhydride is a mixture of ethylene-propylene rubber graphed with maleic anhydride having a weight ratio of 1: 3 to 5: 2. 4. The method of claim 3, wherein the linear segmented thermoplastic elastomer is present in an amount of 15 to 75 wt%, 75 to 20 wt% polymer blend grafted with maleic acid, maleic acid, and 25 to 75 wt% alloying agent, The alloying agent is acrylonitrile-butadiene-styrene terpolymer, styrene-mouse maleic acid copolymer, polyester elastomer, methacrylate-butadiene-styrene terpolymer, polymethyl methacrylate, nitrile rubber, polyethylene ionomer, polyester convexamide And polyphenylene oxide polymers or mixtures thereof. Linear segmented thermoplastic elastomer with rigid and ester segments of 20 to 90% by weight of polycarbonate and 70 to 5% by weight of polyamide based on semi-crystalline aromatic polyamides based on polyurethane or diphenylmethane diisocyanate 10-100% by weight of a compatibilizing compound of the polymer, said compatibilizing compound having at least one functional group soluble in polycarbonate and at least one functional group soluble in polyamide, 0-90% by weight impact modifier, and 0-90% 20 to 2% by weight of poly and 80% by weight of the alloying agent is mixed with a compatibilizer under shear conditions to form a uniform mixture; Forming a homogeneous molten mass of thermoplastic from the mixture to form an extrudate; And cutting the extrudate into pellets for use in shaping and extruding articles made from polymer blend pellets made of polycarbonate and polyamide. Way. 7. The method of claim 6 wherein the forming step injects the mixed material into a compounding extruder and heats the particulate mixture to a temperature of 480 to 550 ° F. at a pressure of 500 to 1500 psi to form the molten mass and shears the molten mass. Extruding under conditions to form an extrudate, wherein the polymer blend of polycarbonate and polyamide is prepared. 8. The method of claim 6 or 7, wherein the molten mass is subjected to an extruder screw speed of 100 to 300 RPM to uniformly mix the components. 8. Process according to claim 6 or 7, wherein the extrudate is cut in water. 8. Process according to claim 6 or 7, wherein the pellets are cooled before the pellets are cut.